1. Field of the Invention
This invention generally pertains to urea-aldehyde resins and more particularly to ureido-terminated polyoxyalkylene-aldehyde condensation products.
2. Prior Art
Urea-aldehyde resins are well known in the art. The most common is the condensation product of urea and formaldehyde. Valuable resinous condensation products can also be obtained by condensing compounds having, in general, one or more terminal ureido or thioureido groups with aldehydes such as formaldehyde or formaldehyde producing compounds. The condensation reactions proceed rapidly under facile conditions. The physical characteristics of the condensate can be varied by choice of the ureido or thioureido terminated compound utilized.
Generally ureido and thioureido terminated compounds, including aliphatic or aromatic diureides, are well known. For example it has been disclosed in U.S. Pat. No. 2,145,242 to Arnold that diureido terminated aliphatic compounds can be produced by reacting an aliphatic diamine with urea. Additionally, polyalkylenepolyamine-containing compounds having primary or secondary amine termination are shown to form ureido containing compounds. For example, triethylenetetramine can be reacted with urea at temperatures of 120.degree. C to 160.degree. C to form thermoplastic resinous polymers soluble in alcohols, ketones, and esters but insoluble in hydrocarbons and only limitedly soluble in water.
Further, it has been disclosed that aliphatic primary diamines and particularly those wherein the amine groups are separated by alkylene hydrocarbons yield crystalline monomeric compounds when reacted with urea. These compounds have a relatively high melting point, i.e., 180.degree. C-190.degree. C and are relatively insoluble in even boiling alcohol. Additionally, Arnold discloses that mono oxy-containing amines yield ureas which are similar in characteristic.
It has now been discovered that polyether-containing urea-formaldehyde resins can be easily produced in homogeneous, aqueous solution using aldenydes or aldehyde-forming compounds and ureido terminated polyoxyalkylenes. The novel condensation products can be conventionally cured to produce a resilient, dense, water containing material which shows minimal shrinkage.